replace a m5 engine with a 3.5?? [Archive] - Bimmerfest - BMW Forums

: replace a m5 engine with a 3.5??

11-20-2009, 09:28 AM
If a 3.5(3.4) M5 engine failed, despite the sacrilege, does anyone know how hard it would be to install a regular 3.5 liter engine from the 535i....or even a later model engine like an m3 engine into the car? The later ones would make more power...the 535i engine could easily be turbocharged and lose the problems of the m5 engine. Could this be done economically? ( no other point if it wasn't economical...otherwise fix the m5 engine....but from what I've read here and on the m5board....ouch!)


11-20-2009, 09:49 AM
I think the more important question is what did you possibly do to kill and M5 motor? Usually the bottom end is bullet proof, and it isn't THAT bad to rebuild the head on them (so long as it isn't warped/cracked). Replace maybe a bent valve or two, have it machined and cleaned, and reassemble will normally never bring the bill above a couple thousand.

But to answer your question the M30 swap isn't too complicated, though like all swaps, it is never a task for the faint at heart, especially if you are doing a turbo. However going to an M50/S50/S52 would never be worth he effort, and you would be much better off going and getting a 525i to do that swap. The cost of a turbo one of these would probably end up costing as much as repairing the head on a S38 with even more headache! Hell even turboing a M30 would probably cost right around the price of a top end rebuilt on an S38.

My advice, find out what is really wrong first with the S38, and then let us know.

11-20-2009, 11:24 AM
Well, I don't own one yet ( m5) but am looking at them. I"m also getting warned ( by reading the posts about them) that they are very pricey to maintain....gaskets replacement leads to another repair etc) and they all talk about the $$$ that i'll need. I"m not hearing the same for the other, yes the turbo will cost ($5,500 I"m reading) but it'll make way more hp and torque than an M5...and thus the attraction. Its relatively easy to get even more boost/power from a turboed engine, not so with an s38. Now, The M5 already has the superior brakes, limited slip differential, suspension ( though the rear is problematic) along with good sport seats, rims, and front bumper....thus my attraction to it.

I welcome all advice as I am new to these cars! i do drive a '93 525i, thought about turboing it, but it has less displacement than the 3.5....then it would need a tranny rebuild ( 3.5 engine tranny most likely won't since all say its stronger). Yeah, I bet some will say just find a good 535i 5spd, I'm looking into that too...but, it still lacks the other things the m5 has.

11-20-2009, 11:27 AM
Everything is a trade off. get what you want. just be willing to go the distance.

11-20-2009, 12:01 PM
Well since you have a 525i/5, I would just get a beater to drive around, and turbo that. The m50, despite only being a 2.5L, is a very capable turbo motor (every bit as the M30). Just ask 5mall5nail on bimmerforums.

Personally I think the question really becomes how much power you really want? If you want 300 or so I would say stay with the S38. While it does cost more to maintain, the package as a whole is almost perfect, and no matter what, you will probably delete the SLS for a conventional system. If you want 350-450, then yes I would say go for a turbo s50/m50/m30 and spend the extra money on upgraded brakes, seats, suspension.

Truth be told there is no right answer here, just what you want to do and how you want to go about doing it; all personal preference.

Alpina Biturbo
11-26-2009, 12:49 PM
IMO .. it looks hars to downgrade an oem M5 to M30B35,,,

by an E34 535 and turbocharge it,,

get another used engine S38B36 and replace the broken one